Alternating-current apparatus



(No Model.) 1

E. & F. W. HEYMANN. ALTERNATING CURRENT APPARATUS.

Patented May 13. 1890.

01? EESES.

UNITED STATES PATENT OFFICE.

EDXVARD HEYMANN AND FRANK \VILLIAM TIEYMANN, OF BOSTON, ASSIGNORS TOJAMES E. MAY N ADIER, TRUS' EE, OF TAUNTON, h[ASSACllIlSE'l".lS.

ALTERNATlNG-CURRENT APPARATUS.

SPECIFICATION forming part of Letters Patent No. 427,571, dated May 18,1890.

To all whom it may concern.-

Be it known that we, EDWARD IIEYMANN and FRANK XVILLIAM HEYMANN, both ofBoston, in the county of Suffolk and State of Massachusetts, haveinvented a new and useful Alternating-Ourrent Apparatus, of which thefollowing is a specification, reference being had to the accompanyingdrawing, forming a part hereof, which is a diagram illusro trating theprinciple of our invention andalso one of its applications.

Solenoids and electro-magnets have long been known as ammeters orcurrent-indicators of continuous or straight currents, and

they have been generally used to modify resistances and for likepurposes; but so far as we know no practical instrument capable of thegeneral uses above indicated has ever been devised for use withalternating ourrents; and the main object of our invention is to furnisha practical apparatus which is operated by variations in currentstrength of a circuit in which the currents rapidly alternate.

2 5 One feature of ourinvention consists in the combination of a corewith a main and an auxiliary coil, both coils forming a part of thealternating circuit; but the main coil is so wound as to magnetize thecore in an opposite sense from its magnetization by the auxiliarycoil-that is to say, the main coil is so wound 011 the core as to makeone end of the core north and the other south at every current, say fromleft to right, and vice versa at every current from right to leftwhilethe auxiliary coil is so Wound that the currents which would be inducedin it by alternations of the magnetism of the core are always in thesame direction as the corresponding alternations in the main coil, aswill be clear from considering the instrument A. (Shown in the diagram,in which the main coil is shown in two parts a a and the auxiliarycoilis marked 7).) Here when the current is from left to rightthat is,from A to A it it traversed the main coil a a, as it does the main coilof the converter 0, it would make the core a a magnet with its southpole on the left and its north pole on the right, and that would inducea current in the auxiliary coil b, whose ,iicn filed June 10,1889.Serial No. 313,784. (No model.)

course would be from left to right in the coil 7) as it is wound in theinstrument A. The other alternationthat is, from right to left, insteadof from left to rightwill reverse the magnetism of core (1?, and willalso reverse the direction of the induced current in the auxiliary coilZ). \Vcre the auxiliary coil. 1) part of a separate and distinct circuitfrom the circuit of which the main coil a a, forms a part, (and this isthe common arrangement where main and auxiliary coils are used, in theconverter (1,) the counter electro-motive force produced by therapidly-alternating magnetism of the core a would practically preventthe passage of any appreciable current through the main coil to a,except when the auxiliary coil Z) is in closed circuit; and our theoryof the matter is that a current is in truth induced in the auxiliarycoil Z) by the rapid alternations of the magnetism of the core a in ourdevice A, almost precisely as a current is induced in the auxiliary coilof the converter O, and as is now well understood by all skilled in theart. It will, however, be clear that by our new arrangement of anauxiliary coil l) with relation to the main coil a a the auxiliary coilis always part of aclosed circuit whenever an alternating current existsin the main coil a a, and consequently in our device the alternatingcurrent flows from A to A and from A to A with trifling resistance andas if the core a were not present in the coils, while at the same timethe core a is at tracted by the main coil a a in almost precisely thesame manner as if the current were 8 5 always in the same directionthrough the coil a a and the auxiliary coil 1) were absent.

One of the main advantages of this first feature of our invention isthat we are enabled by its use to automatically regulate the 0electro-motive force of an alternating-current dynamo, as will be nowexplained.

In the drawing, D represents an alternating-current dynamo, and D itsexciter, the straight current produced by the exciter D being carriedthrough the coils of the fieldmagnet of the alternating dynamo D. lVhenthe dynamo D is used, as indicated in the diagram, to energize a numberof converters in multiple, it is necessary that its eleetro- IOO motiveforce be kept practically constant, and to do this the current from theexciter D should be varied in strength, and this is commonly done by avariable resistance R; but heretofore it has been customary for anattendant to keep watch of a lamp and to vary the resistance R by handwhenever that lamp varied in glow. In our invention this regulation ofthe resistance R is accomplished automatically byour device A, as willbe clear from the drawing without detailed description of theconstruction of the resistance R, which maybe of any suitable type. Itwill be clear to all skilled in the art that any decrease in the loadwill tend to cause an increase in the difference of potential betweenthe leads \V \V and any increase in the load a decrease in thatdifference of potential; but when the difference of potential tends toincrease the current strength between the terminalsAA is alsoincreased,and the resistance R thereby increased by the action of thecore a under the influence of the increased current through the coil aa, and that increase of the resistance R which is in the fie1d circuitof the cxciterD decreases the output of eXcit-er D, and therebypreventsincrease of the difference of potential between the leads V l'In like manner any increase in the load tends to decrease the differenceof potential between the leads \V N and thereby to decrease the currentstrength from A to A but this lessens the pull of the coil to a upon thecore (6 and diminishes the resistance of the rheostat R, and thatincreases the current strength in the field-circuit of exciter D, andthereby prevents a fall in the difference of potential of dynamo D.

Vhile We have shown both features of our invention as applied topreserving a constant difference of potential between the terminals ofan alternating-current dynamo, it will be obvious to all skilled in theart that our invention can also be utilized to produce a constantcurrent by varying the difference of potential between the terminals ofan alternating-current dynamo, and it will also be clear that ourcombination of the core a and the main coil Ct at and the auxiliarycoil 1) is generally applicable to a large variety of uses withalternating currents.

\Vc are aware that attempts have been made to automatically regulate thecircuit of an exciter by variation in the current strength in theexternal circuit of an alternating-current dynamo whose field-coils werein the eXcitercircuit, (see, for exan1ple,latents No. 366,523 of 1887,and No. 392,370 of 1888,) and we do not claim, broadly, the regulationof an exciter-circuit by variation of the external circuit of analternating-current dynamo.

hat we claim as our invention is 1. In combination, core (L2, main coila a, and auxiliary coil 7), the coils being wound to make the directionof any alternating currents induced in coil 11 the same as the directionof the inducing alternating currents traversing coil to a, and the maincoil a a serving as a solenoid for the core (1 all substantially asdescribed.

2. In combination, alternat-ing-ciu'rent dynamo D, its exciter D, core(t main coil a a, auxiliary coil b, wound upon the middle part of core ato make the direction of the cue rents induced in coil 7) the same asthe direc tion of the ind ucing-currents in coil (1, a, and variableresistance R, the position of the core a with relation to coil a aregulating the resistance R, all substantially as described.

FRANK \VILLIAM IIEYMANN. EDWARD IIEYMANN. \Vitnesses:

H. C. YOUNG, JOHN R. Snow.

